The invention relates generally to container inspection apparatus and deals more particularly with a lean detector for containers and other products.
Glass containers are often manufactured at a high rate by an individual section machine, and it is important to inspect the containers for lean. Lean is a condition typically characterized by inclination of a center axis of the container. Containers exhibiting excessive lean are ordinarily rejected.
Various lean detectors of containers have been previously known. For example, in U.S. Pat. No. 3,754,123 to Keller, a lean detector comprises sources of light which project two mutually perpendicular light beam patterns across a continuously moving conveyor toward an array of light sensitive devices arranged in pairs for inspecting the silhouette of articles on the conveyor. The lean inspection circuitry includes a pulse generator and counter capable of providing two signals indicative of the degree of lean of the article in two mutually perpendicular directions. These signals are squared and summed to indicate the total amount of lean of the container and then compared to a predetermined level to determine whether the container leans excessively.
U.S. Pat. No. 3,716,136 to Birner et al discloses apparatus for inspecting the peripheral portions of an article to determine whether the shape of the article is acceptable. If the peripheral portions are in predetermined relation to one another as detected by a plurality of light sources aimed at the peripheral portions, then the container has a suitable shape.
Some of the previously known lean detectors require an excessive number of light sources and detectors, and precise positioning of the light sources at precise angles relative to each other and the containers.
Accordingly, a general object of the present invention is to provide a lean detector which requires a minimal number of light sources and detectors, and does not require precise positioning of the light sources relative to each other or the containers.
Another general object of the present invention is to provide suitable processes to implement the foregoing object.